1. Field of the Invention
The present invention relates to an image forming device and especially relates to such a structure thereof as the junction between a developing unit and a toner hopper can be rationally accomplished.
2. Description of the Prior Art
FIG. 12 is a perspective view showing a separated condition of a developing unit 1 and a toner hopper 2, which are to be used in a conventional image forming device in the background of the present invention. Toner which is supplied through a toner supplying port 3 of the toner hopper 2, which is arranged upwards of the developing unit 1, is conveyed to this side in FIG. 12 by means of a spiral toner conveyor roller (not illustrated) which is installed downwards of the toner hopper 2, and toner is subsequently supplied from an opening 6 of a toner discharge shutter 5 to a toner replenishing port 7 of the developing unit.
And the toner is evenly supplied to a developing roller by means of a conveyor roller or an agitating roller (both of which are not illustrated) which are provided in the developing unit 1.
Such an image forming device is so composed that the developing unit 1 can be drawn out from the image forming device proper by pulling out the developing unit 1 in the axial direction of the developing roller (i.e., the direction of an arrow "A") when carrying out maintenance and inspection work, for instance, for treatment of a jammed paper. However, at this time, as the toner hopper 2 remains installed in the image forming device, such a structure that the toner replenishing port 7 of the developing unit 1 and the toner discharge shutter 5 of the toner hopper 2 can slide relative to each other has been employed.
Therefore, it is necessary to secure a high positioning accuracy at this sliding portion. In the case that the positioning accuracy is not good and there must be a clearance between the toner replenishing port 7 and the toner discharge shutter 5, there are such problems as toner may leak or on the contrary, the toner replenishing port 7 and the toner discharge shutter 5 may be damaged by sliding thereof unless there is a prompt allowance therebetween.
As it is necessary to secure a high positioning accuracy at the sliding portion as shown in the above, it is much desired that the area of the sliding portion be made as small as possible, and the junction portion (the sliding portion) which is a supplying channel through which toner is supplied from the toner hopper 2 to the developing unit 1 is also required to be made small. For this purpose, after the toner is supplied to the toner replenishing port 7 of the developing unit 1 once the toner in the toner hopper 2 is conveyed to the side of the toner discharge shutter 5 at one side of the toner hopper 2, the toner which is supplied to.. the toner replenishing port 7 must be conveyed through out the range of the developing unit 1. Therefore, the toner supplying process may become very complicated, thereby causing such a structure as shown in the above to result in an increased cost of production.